1. Field of Invention
This invention relates to ophthalmic surgery and more particularly to cutting the cornea of an eye.
2. Description of the Prior Art
The cornea, the outer tissue of an eye, is frequently the subject matter of ophthalmic surgery. In a corneal transplant, for example, a central portion of the cornea of a patient's eye is surgically removed. Preferably, the surgical removal is by a cut that is parallel to the axis of the patient's eye. The surgical removal leaves a hole in the patient's eye that is circularly symmetric about the axis thereof.
The hole is filled by a central portion of the cornea of an eye of a donor. Analogous to the hole, the central portion of the donor's cornea is circularly symmetric about the axis of the donor's cornea. Moreover, when a cut of the donor's cornea is made to provide the central portion thereof, the cut is preferably parallel to the axis of the donor's cornea.
Usually, the cut of the donor's cornea is made in a cutting fixture by a hollow cylindrical blade that has a cutting edge at one end. The donor's cornea is placed upon a work surface of the fixture and the blade is advanced along its axis towards the donor's cornea, thereby bringing the cutting edge against the donor's cornea. Because the blade is cylindrical, the cut of the donor's cornea is circular.
It should be appreciated that the desired diameter of the cut of the donor's cornea is usually, if not always, in a range of six and one-half millimeters to eleven millimeters. Typically, the desired diameter of the cut of the donor's cornea is in a two millimeter range--a range of seven to nine millimeters.
When the fixture is suitable for use with a blade with a cutting edge of one diameter, it is usually not suitable for use with blades with cutting edges of other diameters. Additionally, a simplified fixture for maintaining the work surface in a desired space relationship to a cutting edge is unknown in the prior art.